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Can Fish Eat Chocolate? (Read This First!)

Having pet fish is a fun and satisfying hobby. The most fun part of the fish-keeping is feeding them. They eat everything that fits into their mouth. But should you feed them chocolate? Here is a detailed article about it.

Can fish eat chocolate?

Fish should never eat chocolate. It’s very harmful to the fish and the tank. Consuming fat can be dangerous for them. Most chocolate contains almost 33% fat. Sugar in chocolate can destroy your tank’s water quality and beneficial microbes that live in the aquarium.

The mistake that most new fish keepers do is, they feed their fish with random things out of curiosity. But it can be very dangerous for the fish. The first rule of fish keeping is, you can’t experiment with your fish, be sure before doing something. 

There is a lot of food you can feed your fish. But getting the knowledge before feeding is important.

Now let’s talk about chocolate, it is not good for your fish health and worst for your aquarium. The fat can make the fish sick and the sugar will destroy the natural cycling of your aquarium.

Moreover, chocolate is not a natural fish food. Cocoa in chocolate has no beneficial nutrients for fish. Fish food should contain protein, fiber, and various vitamins for their growth.

Fish may get digestive problems and they will get unhealthy fat if you feed them food with high-fat food. More than 3% fat is dangerous for your fish health. 

Well, you may not feed chocolate regularly to your fish. Eating chocolate a few times will not harm your fish. The problem is, the sugar will destroy your water quality. 

We will discuss this further in the next sections. For now, let’s find out if you can feed those fish with chocolate.


You can’t feed your betta fish with chocolate. Bettas need high protein foods as they are carnivorous. Chocolate can’t fulfill the criteria. In nature, betta lives on small insects and insect larvae. There are foods for aquarium bettas.

Bettas have long beautiful fins and they come in various colors. If you don’t provide them with proper nutritious food, their beauty will fade and may lead to loss of life.

Koi fish:

No, chocolate is not a good food choice for koi fish. They live on algae, plants, insects, worms, and seeds in nature. There are many things you can feed your koi fish. But food with fat and sugar is harmful to them.


Goldfish can’t eat chocolate. Goldfish need a tank with proper cycling and a good microbial community to live longer. Chocolate can make your goldfish tank toxic. If you want to feed your goldfish they will love, go for some live food. Live foods can be found in pet shops.


Guppies can’t eat chocolate. Guppies are one of the most popular fish among hobbyists. Although guppies are very hardy fish, it’s dangerous for them. Guppy fish are known for their frequent fry-laying. If a female gets too much fat, it may expire while laying fries. 

Tropical fish:

Chocolate is toxic to almost all tropical fishes. Tropical fishes need a tank with proper filtration and oxygenated water. Chocolate can harm the tank’s biological filtration and oxygen level. 

Is chocolate poisonous to fish? Can fish pass ayaw if they eat chocolate?

Yes, chocolate is poisonous to fish. Chocolate contains cocoa and it can be toxic to many fish species. Fish may lose appetite and get sick by eating chocolate.

High-fat foods are not natural for them. Their metabolism can’t process high-fat foods. As a result, fish may get digestive problems and pass away.

It’s not safe even if your fish can consume chocolate and digest it. The fish will get fat quickly and become immunocompromised.

But, you would not have to wait that long, chocolate will harm your aquarium water quality seriously and that can hurt your fish within a few days if you don’t take any steps.

If you have some hardy type of fish like guppies, you may get a chance to fix it. But, some sensitive fish species will expire faster if you feed them wrong. However, it also depends on how much chocolate you dropped into the water. 

Does chocolate attract fish?

Not really. Fish will eat chocolate anyway. But they will not become attracted to it.

If you really want to impress your fish and feed them something they will love, go for a live food option. Live insects and worms have all the nutritional value a fish food should have.

Moreover, fishes will enjoy chasing and munching on live insects. Live food also makes them happy and lively.

But, it’s better to feed them live food as a treat. Feeding too much live food can cause internal parasites. Always get live foods from reliable sources. A pet shop should have different types of them.

If you love your fish and have some time for them, prepare their homemade foods. Eating different types of food can fulfill their nutritional requirements and make them happy. 

Follow the next section for alternative food sources for your pet fish.

4 reasons why fish cannot eat chocolate

There are several problems with feeding your fish chocolate. 

High-fat content:

Chocolate has a high-fat content that creates various problems for your fish. Fish may get a digestive disease, become inactive and fat. A fat fish is prone to get other diseases easily.

Lacks essential nutritions:

Chocolate has high sugar and fat content but nutrition for fish’s metabolic activity. Fish needs high protein food that must have very low fat. They need fiber for their digestive health. 

Calcium and phosphorus are the most essential nutrients for fish. If they don’t get the necessary nutrients in their regular food they may get sick.

Water quality:

Feeding chocolate once or twice usually would not affect your fish but water quality will reduce massively. Chocolate and sugar will dissolve in water. The sugar will feed the yeast and bacteria in your aquarium. 

An aquarium should have more nitrifying bacteria so they can process the fish waste and keep the water liveable. But if sugar-consuming microbes become abundant, they will compete with beneficial bacteria that help to keep aquarium water. 

The sugar-consuming bacteria will break the sugar into carbon dioxide which will harm the oxygen level of your tank. They also produce alcohol in water which will make tank water highly toxic to fish.

Cocoa toxicity:

Cocoa can be harmful to some fishes. Fish will act weirdly if cocoa is toxic to them. It may cause fish passing or disease within a short period.

What else can fish eat besides fish food?

Run out of fish food? Don’t worry! There are dozens of human foods that fish can consume. Before jumping on the list, always remember, no matter what you are feeding, overfeeding can be dangerous for your fish.

Egg yolk:

Egg yolk is a very nutritious food for your fish. But it will reduce the water quality faster than other food. A little bit of egg yolk is enough.

There is a thumbs rule to determine the amount of food. Feed them an amount of food that fishes can finish within 2 minutes.


Vegetables are an important part of the aquarium fish diet. You should feed once or twice a week. Vegetables provide good fiber and nutrition to fish. 

Most of the vegetables are good for them. Peas, cauliflower, potato, papaya, pumpkin, cucumber, carrot, etc. are good vegetables to feed your fish.

Cut the vegetables into small pieces and boil them before feeding.

Beef liver:

Beef livers have high protein content and low-fat content in them. So they are an excellent choice as fish foods. Boil the liver and smash before feeding.

Boiled shrimps:

Fish foods use shrimp as fish food as they can contain high amounts of protein. Boiled shrimps can be fed to your fish after cutting them into very small pieces.

Can sugar hurt fish?

Sugar can hurt your fish. If you pour sugar in your aquarium in high concentration, it will hurt the beneficial bacteria and reduce oxygen level and water quality.

Even a small amount of sugar can also increase the growth of sugar consuming harmful microbes. The microbes produce toxic products that will harm your fish.

So, never use sugar in your fish tank and never feed anything that has sugar in it. However, if you made a mistake, it’s fixable most of the time if you change 40-50% water for 3-4 consecutive days.

Final thoughts

Fishes can not eat chocolate as it contains high fat and sugar. Fat can make them sick and works like slow poison and sugar can destroy your fish tank’s nitrogen cycling and help produce harmful bacterias. It’s probably among the worst things you can feed your pet fish.